I. Field of the Invention
This invention relates to a device for the introduction of air or other pressurized gas into dry bulk material to fluidize the material for efficient pneumatic transfer.
II. Description of the Prior Art
In the prior art, aeration devices are well known for use in pneumatic trailer tanks, rail cars, storage tanks and the like. Such devices introduce air into containers to aerate material stored within the containers. Such prior art devices may be porous to permit the flow of air through the device or may consist of flexible elements which provide a seal when air pressure is terminated but permit passage of air from the device into the container when air pressure is initiated. Examples of the latter may be found in U.S. Pat. No. 4,172,539 to Botkin dated Oct. 30, 1979 and my prior patent, U.S. Pat. No. 3,929,261 dated Dec. 30, 1975.
U.S. Pat. No. 4,172,539 teaches an aerator for a hopper container. The aeration device includes a body member having a radially projecting disk which is secured to an inner wall of a hopper by means of a cup on an exterior wall. The cup has a bolt which threadedly engages a stem portion of the disk extending through a hole in the container wall. The disk portion has an axially aligned retaining head which receives an axially aligned cylindrical central portion of a resilient skirt which rests upon the disk in face-to-face relationship. A plurality of bores extends through the disk portion providing gas flow communication between the cup and a manifold defined between the disk and the skirt. When pressurized air is admitted to the cup, the air passes through the bore and into the manifold and forces the skirt away from the disk whereby the air flows into the container to aerate material therein. In addition to the embodiment just described, U.S. Pat. No. 4,172,539 discloses alternative embodiments all of which show a resilient skirt member which rests in face-to-face relation over a solid member and covering air passages between a pressurized source and an interior of the container.
U.S. Pat. No. 3,929,261 was issued to me on Dec. 30, 1975. The patent teaches an aeration device which comprises a cone-shaped support which is affixed to the wall of a container and extends into the interior of the container. The device has an air inlet on an end adapted to be connected to a source of air exterior of the container. The cone-shaped support has a plurality of holes extending through its conical walls. A cone-shaped flap, shaped complementary to the support, is closely fitted onto the support with the flap closing the holes. The flap has an open large diameter end adjacent the container wall which flexes away from the support when pressurized air is admitted to the cone-shaped support. When the flap so flexes, air passes through the openings in the cone walls and passes between the cone and the flap toward the container wall and into the container to aerate material within the container. To secure the cone-shaped support against the interior of the container wall, a cup member is provided on an exterior of the wall which surrounds an extending end of the cone-shaped support passing through a hole in the container wall. The cup member is provided with an inlet fitting connected to a source of pressurized air. Additionally, the cup member is provided with a threaded fastener extending through a hole in the cup-shaped member and axially aligned with an interior threaded portion of an extending end of the cone-shaped support. The threaded fastener engages the interior threads and draws the cone-shaped support tightly against the container wall.
While the prior art teaches aeration devices such as those described above, there is a continuing need in the art for improvements in aeration devices. Certain problems which continue to plague the art include contamination of the aeration device by pulverulent material within the containers. Such material migrates into the aerator when air flow through the aerator is discontinued or during loading of the material into the container. Also, the restricted flow passages of the prior art aeration devices can generate undesirable back pressure within the aerators. Another problem associated with the prior art is that the flexible skirts of the prior art may reverse and stay reversed thereby exposing the aerator holes when air is not passing through the holes. Finally, many of the prior art devices incorporate the above problems while having an additional problem of taking up a substantial amount of space within the container. The physical dimensions of such aerators present a greater area to be bombarded by pulverulent and abrasive material when it is admitted into the container thereby increasing the possibility of damage to the aerator device over a relatively short period of time.